The C-Terminal Tail of Yersinia pseudotuberculosis YopM Is Critical for Interacting with RSK1 and for Virulence

Abstract

Yersinia spp. undermine the immune responses of infected animals by translocating Yops directly into host cells with a type III secretion system. YopM, a leucine-rich repeat protein, is a critical virulence factor in infection. YopM localizes to both the nucleus and the cytoplasm in cultured cells, interacts with mammalian p90 ribosomal S6 kinase 1 (RSK1), and causes a decrease in NK cell populations in spleens. Little is known about the molecular interaction between YopM and RSK1 and its significance in pathogenesis. We performed a systematic deletion analysis of YopM in Yersinia pseudotuberculosis to determine which regions are required for RSK1 interactions, nuclear localization, virulence, and changes in immune cell populations during infection of mice. Full-length YopM associated with RSK1 in at least two protein complexes in infected cells, and deletion of its C-terminal tail abrogated all RSK1 interactions. The C-terminal tail was required for tissue colonization, as yopM mutants that failed to interact with RSK1 were as defective for tissue colonization as was a ⌬yopM mutant; however, nuclear localization of YopM was not dependent on its RSK1 interaction. Mutants expressing YopM proteins which do not interact with RSK1 caused more pathology than did the ⌬yopM mutant, suggesting that there are other RSK1-independent functions of YopM. Histopathological and flow cytometric analyses of spleens showed that infection with wild-type Y. pseudotuberculosis caused an influx of neutrophils, while mice infected with yopM mutants had increased numbers of macrophages. Decreases in NK cells after Y. pseudotuberculosis infection did not correlate with YopM expression. In conclusion, the C terminus of YopM is essential for RSK1 interactions and for virulence.

Uncovering an Important Role for YopJ in the Inhibition of Caspase-1 in Activated Macrophages and Promoting Yersinia pseudotuberculosis Virulence

“…Activation of RSK1 occurs independently of the upstream kinases ERK1/2 and is sustained because dephosphorylation of RSK1 is prevented in the presence of YopM (50,53). Binding of RSK1 to YopM in Y. pseudotuberculosis-infected macrophages also stimulates the formation of high-molecularweight complexes of RSK1 and YopM (51). The role of RSK1 in inhibition of caspase-1 activation by YopM is unknown.…”

“…In addition to an LRR domain, all YopM isoforms contain a conserved C-terminal tail, which binds to ribosomal S6 protein kinase 1 (RSK1) (50)(51)(52). The YopM C-terminal tail is required for Yersinia virulence (51,52) and inhibition of caspase-1 activation (31).…”

“…The YopM C-terminal tail is required for Yersinia virulence (51,52) and inhibition of caspase-1 activation (31). Binding of YopM to RSK1 induces activation of its kinase activity (50,53).…”

Distinct CCR2+Gr1+Cells Control Growth of theYersinia pestisΔyopMMutant in Liver and Spleen during Systemic Plague

“…Several proteins have been identified as being able to bind YopM: ␣-thrombin (30), ␣1-antitrypsin (19), and the serine/ threonine kinases RSK1 and PRK2, which as a consequence become activated (34)(35)(36). McPhee et al (36) studied i.v.…”

Distribution and Evolution of Yersinia Leucine-Rich Repeat Proteins

“…YopM was further shown to interact with protein kinase C-like 2 (PRK2) and ribosomal S6 kinase 1 (RSK1), causing sustained activation of the kinases by shielding them from phosphatase activity toward two serine residues (15,16). The C terminus and an internal portion of YopM were essential for the interactions with RSK1 and RSK2, respectively, and for the expression of proinflammatory cytokines (17)(18)(19). The interaction of YopM with RSKs and the resultant consequences may explain the observation of interference of YopM with host innate immunity (10,(20)(21)(22)(23).…”